I got on it one after noon. then notice that it started having a slight miss inbetween 1500-2000 Rpms but after 2 it would go away. kept driving it toward the end of the week the miss went away. then driving down the interstate with my dad a wrx came up on us and Ofc we raced on the last pull i was at about 4k rpm and it acted like it was hitting the rev limiter i guess it was missing so bad.. Anyone know what this could be?

Oh yeah i have a 2000 mustang gt and i have just recently changed the Iac valve. Thanks in advance

 

check your coil packs

 

whats the best way going about that?

 

check your MAF too...that exact same thing happened to me on my old 99 maxima

 

Update: i now notice that it runs fine while cold but once it starts heating up it seems to run like crap again.

 

+1

That's what it sounds like to me.

Also, do you drive a stick or an automatic? Mine used to act silly a lot too in my auto v6, and it was sporadic like how you're mentioning it, then I noticed I was low in transmission fluid and it caused me to jump all over the place. Maybe check your tranny fluid to be safe/

 

Sorry i should have mentioned that its a stick

 

Cop's sounds like your culprit.

 

uh could u explain a little better please

 

it runs fine cold then runs crappy warm?... So once the car goes into closed loop it acts up..... Check the 02 sensors, Maybe wiring on them got messed up or they can be bad all together, when you first run your car it runs off a preset air/fuel ratio i believe and when it warms up it starts using the information the car is collecting.... So the pre-cat sensors could be a problem. Also Clean the MAF too.. I wouldnt suspect your COP's as that should be a constant problem... Are you throwing any codes? Those would def steer you in correct direction.